It is not unusual for drugs to be derived from substances that in
other contexts would be considered dangerous. Many cancer
medications are in this category.
It is also common for drugs that are licensed for a particular
condition to be used "off label" to treat other problems.
So even though botulinum toxin (better known as Botox) is one of
the most powerful nerve poisons known, its rise as a medication in
recent decades is not as startling as some might think.
But all drugs, even the mildest over-the-counter medications,
have unwanted side effects. And as the number of uses for botulinum
toxin grows along with the number of people who use it, healthy or
otherwise, it is no surprise that reports of unwanted effects are
growing, too.
Though this toxin is extremely deadly when ingested, as a muscle
injection it has found a vast clientele among otherwise healthy
people. As Botox Cosmetic by Allergen, it is widely used by many
women and men in affluent countries to relieve the visible ravages
of age, at least temporarily.
A friend recently told me with slight exaggeration that "every
woman" in Argentina in her 40s regularly had Botox injections to
smooth out facial wrinkles, just as casually as she might have her
hair dyed to hide the encroaching gray.
I can only wonder what these women will do in their 50s and 60s,
when wrinkled skin is no longer confined to their faces. Given the
prevalence of ageism and the perennially youthful images paraded
before us in the media, there is no telling to what limits women -
and some men - may go to in an effort to physically deny their age.
Botulinum toxin is produced by the bacterium Clostridium
botulinum.
It grows in the absence of air and has a lethal reputation as a
food contaminant, especially in improperly canned or preserved
foods. It weakens muscles and can cause paralysis, including life-
threatening breathing problems. The toxin acts on peripheral nerve
endings, preventing the release of the neurotransmitter
acetylcholine, which conveys nerve signals to muscles.
In tiny amounts injected into muscle, it can relieve spasms by
causing muscles to relax. The effect lasts for months; when it wears
off, the toxin can be reinjected.
The toxin was first used as a drug in the 1970s to treat
strabismus, deviant eye muscles that cause double vision. It has
since proved remarkably effective in treating all manner of problems
caused by overactive muscles, like neck and limb spasms, unwanted
movements, abnormal postures, excessive sweating and pain associated
with various disorders, including migraine headaches. One of its
newest uses, off label, is treating overactive bladder that is
unresponsive to other remedies.
Dr. Jean Carruthers, an ophthalmologist at the University of
British Columbia who in 1987 was among the first to observe Botox's
cosmetic potential, has likened it to penicillin both for its
versatility and for its derivation from a common bacterium.
Carruthers and her husband, Arthur, a dermatologist, noted that
patients she treated with Botox to relax spastic eye muscles also
often experienced a smoothing of frown lines between their brows.
Although there are seven types of the toxin, each with a specific
mode of action, just two, A and B, are currently used medically. Of
the products available in the United States, Botox and Botox
Cosmetic are derived from botulinum toxin A and Myobloc from B. The
cosmetic formulation uses a much lower dose of the toxin than the
one used to treat major muscle spasms.
In February, the Food and Drug Administration, which has a
continuing safety review of these products, notified the public
about reports of ill effects associated with the drugs. Most of the
serious cases resulted from medical, not cosmetic, uses of the
toxin. Medical treatments typically require much larger doses, and
many of the patients have other health problems that increase their
risk.
The reactions, which included serious and sometimes deadly
effects like respiratory failure, involved a range of doses and
uses, many of them off label. The most severe reactions occurred in
children treated for limb spasticity associated with cerebral palsy,
an off-label use in children and adults.
Because this safety review depends on voluntary reports from
medical and patient sources, it is often not possible to tell
exactly what is to blame for the unwanted effects - poor technique,
wrong dosage, an underlying medical problem or a hazard of the drug
itself.
Public Citizen, a consumer advocacy organization in Washington,
has petitioned the drug agency to force manufacturers to warn
doctors about the reported complications. The group reviewed the
agency's adverse-event reports and found 180 cases of serious
effects like pneumonia and difficulty swallowing and breathing, as
well as 16 deaths. In September 2005, the U.S. Centers for Disease
Control and Prevention reviewed 1,437 adverse reports: 406 after
medical use of Botox (217 of them serious effects) and 1,031 after
cosmetic use (36 of them serious).
The proportion of serious reports was 33-fold higher for patients
treated for medical problems than for those receiving cosmetic
treatments.
Although it has long been known that injecting the toxin can
cause unwanted effects in adjacent muscles - for example, injections
to smooth creases around the eyes may cause temporary drooping of
the eyelids - recent concerns involve what are called systemic
reactions, or effects on distant muscles.
Dermatologists who use the drug for wrinkle reduction say that in
experienced hands and properly diluted and administered, Botox is
extremely safe. The worst disasters have occurred when unqualified
practitioners administered the drug.
The drug agency has told doctors who use the toxin to give
patients and their caregivers information about the signs and
symptoms of adverse effects and the need to seek "immediate medical
attention if they have worsening or unexpected difficulty swallowing
or talking, trouble breathing or muscle weakness." Doctors and
patients should also know that adverse effects do not always occur
right away, the agency said, but may show up even weeks after
treatment.
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